The high voltage is used to bias the Silicon Drift Detector of the SVT. It is essential that the voltages be set at well defined values and stable over time. The task of the Control System is to set those voltages, to monitor they remain set at the requested value during the running periods and that the current the power supplies provide does not exceed prescribed tolerances beyond which the detector and power supply good operation could be jeopardized.
There will be 36 HV powers supplies (Lecroy 1440) each connected to the 36 detector ladders. The power supplies will have the ability to supply voltage in the range X to Y. The supplies will be connected to a Lecroy 1131 interface and will thus be setable and readable by the Control System. The Control system will be able to set voltages, read the values requested as registered by the controllers, the actual values supplied to the detectors, as well as the output current supplied by the power units. The voltage affects critically the performance of the detector and will thus be under tight tolerance. Likewise, the current will also have tolerance limits to insure the detectors are not destroyed by excessive currents.
Requirement:
The HV Control System Software has to handle 36 power supplies.
Justification:
There are 36 supplies.
Status:
Under discussion
Requirement:
The HV Control System Software has to be able to set High Voltage values of all 36 supplies independently.
Justification:
The different detectors may be operated at slightly different voltages so all supplies should settable and controlled independently.
Status:
Under discussion
Requirement:
The HV Control System Software has to be able to read requested High Voltage values of all 36 supplies independently.
Justification:
The different detectors may be operated at slightly different voltages so all supplies should settable and controlled independently.
Status:
Under discussion
Requirement:
The HV Control System Software has to be able to read actual High Voltage values of all 36 supplies independently.
Justification:
The different detectors may be operated at slightly different voltages so all supplies should settable and controlled independently.
Status:
Under discussion
Requirement:
The HV Control System Software has to be able to read actual current values supplied by all 36 supplies independently.
Justification:
The different detectors may be operated at slightly different voltages so all supplies should settable and controlled independently.
Status:
Under discussion
Requirement:
The HV Control System Software has to be able to set the power supplies individualy or collectively to ON, OFF or STANDBY.
Justification:
Justification of requirement
Status:
Under discussion
Requirement:
The HV Control System Software has to be able to probe the supplies to determine their state i.e. ON, OFF or STANDBY.
Justification:
It is thus possible to compare the deisred state with the actual state.
Status:
Under discussion
Requirement:
The HV Control System Software has to be able to set tolerances (high and low) on the admissible actual voltage returned by the supplies.
Justification:
The performance of the detector depends critically on the stability of the voltages.
Status:
Under discussion
Requirement:
The HV Control System Software has to be able to set tolerances (high and low) on the admissible actual current output by the supplies.
Justification:
The performance and safety of the detector depends might be affected by excessive current output.
Status:
Under discussion
Requirement:
The HV Control System Software issues an alarm if one or many of the actual voltage bias are found to exceed tolerances.
Justification:
Justification of requirement
Status:
Under discussion
Requirement:
The HV Control System Software issues an alarm if one or many of the actual current output are found to exceed tolerances.
Justification:
Status:
Under discussion
Requirement:
The HV Control System Software issues an alarm if one or many of the power supplies are found in a state (ON, OFF, or STANDBY) different than the expected state.
Justification:
This is both a security and safety issue.
Status:
Under discussion
Requirement:
The HV Control System Software issues an alarm if one or many of the power supplies hardware interface fails to respond to request after prescribed number of retries.
Justification:
It is essential to be able to communicate with the supplies to find their status and the voltages being supplied to the detector.
Status:
Under discussion
Requirement:
The HV Control System Software archives the values of voltage read with a time stamp when these differ from the prescribed value by more than X volts . Justification: It is thus possible to map the history of the voltages and correlate this information with data taken by the data acquisition system.
Status:
Under discussion
Requirement:
The HV Control System Software archives the values of currents read with a time stamp when these differ from the last value read by more than X micro-amps.
Justification:
It is thus possible to map the history of the currents and correlate this information with data taken by the data acquisition system.
Status:
Under discussion
Requirement:
The HV Control System Software must be able to perform on individual, a subset or all HV channels READ, SET, and MONITOR operations.
Justification:
The READ operations consist of probing the supplies for state or parameter values. The SET operations consist of requesting the supplies to change state or set parameter to new values. The Monitor operations involve a combination of READ operations at regular time intervals to determine the state and values of the parameters, check that they are within tolerances, and issue alarms in case they are not.
Status:
Under discussion
Requirement:
The frequency of READ requests performed by the MONITOR task is user set-able but should have a default value of 0.1 Hz.
Justification:
Justification of requirement
Status:
Under discussion
Requirement:
The number and identity of HV supplies actively monitored should be user selectable.
Justification:
It is thus possible to de-activate the monitoring of a known faulty channel and continue operation.
Status:
Under discussion
Requirement:
statement of requirement
Justification:
justification of requirement